International environmental concern has been focused on the adverse role endocrine disrupter play on reproduction and development of living things. Currently, there is not available bioassay to quickly and reliably test for the presence of endocrine disruptors, such as pesticides and herbicides in the environment. This project will demonstrate feasibility of a fast, efficient reproduction bioassay to screen for endocrine disruptors utilizing in vivo Daphnia in aquatic systems. We intend to produce an innovative, accurate, sensitive 6-day bioassay test kit providing a new screening strategy and generating information in a shorter time span than other bioassays. No current assay measures effects during the sexual phase of the life-cycle and they provide no information on sex ratio or developmental changes. This bioassay has commercial potential of being used in environmental testing labs engaged in the testing and screening of freshwater, also in evaluation of toxic effects of individual chemical formulations for product testing, or pesticide registration, required by federal agencies. It is anticipated that this research will contribute to our understanding of environmental chemicals and their generation effect on wildlife and humans. Bioassay results could prove invaluable in developing environmental policy, monitoring water quality and warning of potential human health problems. Proposed commercial applications: none